In the construction industry, the need for manipulating soil and other bases for construction is frequently encountered. This need typically occurs in the construction of buildings, paved roads and parking lots and other improvements. Often, the surface upon which a structure will be constructed has insufficient stability such that it will collapse during construction or some time thereafter. In order to strengthen the ground surface, the ground surface is treated with lime, concrete or other additives. Such treatment is typically performed at a depth of sixteen inches from the ground surface. If the ground is wet, the earth typically requires multiple treatments at four inch intervals. Such treatment usually dries the ground and makes it sufficiently hard to serve as a base for construction.
In order to provide such treatment, soil stabilizers of various designs have been used. Typically, soil stabilizers include a drum portion supported by four wheels. The drum portion houses a rotor which cuts the earth and causes the earth under the drum portion to be mixed with lime, concrete and/or other additives. The treated earth then exits the area under the drum and is positioned at the desired depth.
Typical soil stabilizers weigh as much as 60,000 lbs. Such weight causes the underlying earth to undergo extreme compression. Frequently, any soft patch of earth is more greatly compressed than any neighboring hard-packed earth. Such differences in compression can cause ruts which impact the wheels of the soil stabilizing vehicles. The wheels transfer the impact force to the vehicles and cause the vehicles to experience bounce, in which the weight of the vehicles is transferred up and down as the vehicles move along. The bounce of the vehicles, in turn, causes the rotor to be moved up and down and to cut the earth at varying depths. Under these circumstances, the depth of a cut cannot be guaranteed by making a single pass over an area of ground. Therefore, operators often make several passes with the rotor positioned deeper than necessary in order to ensure that soil at a lesser depth is properly treated. For instance, for treatment at a depth of eleven inches, an operator may drive a soil stabilizer over an area of ground three times with the rotor positioned twenty inches deep. Such treatment is not efficient use of labor, materials or fuel.
Furthermore, soil stabilizers often encounter difficult conditions in which traction is poor and the bottom edge encounters substantial resistance. In such conditions, the stabilizer operator may not be able to get the stabilizer to move forward to make the desired cut. It is known in the field that operators may “wiggle” the wheels side to side or otherwise encourage the stabilizer's wheels to obtain better traction to allow forward movement. Such wiggling frequently causes the stabilizer to bounce which further impairs the ability to obtain a cut and soil treatment at the appropriate depth. Another way to overcome the inability to move forward, is for the operator to make a cut at a shallower depth. Of course, treatment at a shallower depth may not provide sufficient soil stability and may lead to construction problems.
Another problem is frequently encountered by soil stabilizers which are used on hill sides or other uneven terrain, typically in cases where the soil treatment is intended to control movement of water. Often soil stabilizers employed in such use slide down the hillside or even roll over during operation. Sliding is typically caused by the poor traction of the soil stabilizer's wheels. Rolling over usually occurs when the uphill wheel of the soil stabilizer encounters a bump or rut which causes the uphill tire to bounce. The upward shift in weight causes the center of gravity to shift upward and results in the soil stabilizer rolling over.
Another problem faced by soil stabilizers is the compaction of earth under the soil stabilizer wheels in the direction of travel. This problem is aggravated when working in wet areas where a soil stabilizer may sink into the earth on its first pass across a path, resulting in a large delay in completing the job. Therefore, the resistance to sinking into soil, or flotation, would be highly desirable for a soil stabilizer.
As can be seen, regardless of the type of soil stabilizer utilized, several problems are encountered when removing and treating large amounts of earth. Therefore, in view of these problems and their consequences, there is a need in the field of earth working for an improved soil stabilizer.